DESCRIPTION (DESCRIPTION (provided by applicant): The goal of this research is to characterize the mechanisms that mediate short-term visual memory decay. The project will involve conducting a series of psychophysical experiments to pinpoint the effects of memory decay within the context of a standard signal detection model of visual information processing. One of the key assumptions made by nearly all current models of short-term visual memory is that temporal decay is due to a progressive increase in internal noise over time. My preliminary results from pilot experiments suggest that this assumption is in fact incorrect, and that short-term visual memory decay is a deterministic rather than stochastic process. This result is difficult to reconcile with current models of short-term visual memory, and potentially places strong new constraints on the kinds of mechanisms that mediate the decay process. Thus, one goal of the proposed research will be to replicate and extend my preliminary experiments. A second goal will be to conduct an additional series of experiments to determine the specific nature of the deterministic processes that are responsible for short-term visual memory decay. Ultimately, the long-term goal of this work will be to develop a viable quantitative model of short-term visual memory decay. Characterizing the mechanisms involved in the retention of visual short-term memory is of central theoretical importance to forming a more complete understanding of human visual information processing. A more direct health-related application of the present work is to inform the development of techniques to improve the ability of medical imaging technologists to make comparative judgments that require retention of information in short-term visual memory (e.g., making comparisons amongst X-ray displays, etc.). [unreadable] [unreadable]